# NTSB WPR23LA263: Robinson Helicopter R44 II, N163RK, Marble Falls, TX, July 9, 2023 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: July 9, 2023, 09:47 local (14:47 UTC) - Place: Marble Falls, TX - Coordinates: 30.570303, -98.26327 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=30.5703&lon=-98.2633&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute: Fuel contamination](https://openairdocs.org/ntsb-events/193) - Highest injury: No injuries - Injuries: 3 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 192581 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR23LA263 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/192581/pdf - Page: https://openairdocs.org/ntsb/WPR23LA263 ## Probable cause A total loss of engine power due to fuel contamination from an unknown source. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Fluids: fuel](https://openairdocs.org/ntsb-findings/01071010): Aircraft › Fluids/misc hardware · Fluid condition (probable cause); cases with it: [Robinson Helicopter R44 II, 4 cases](https://openairdocs.org/ntsb-findings/01071010/cases.md?model=7640122), [All aircraft, 1,695 cases](https://openairdocs.org/ntsb-findings/01071010/cases.md) - [Fuel system: fuel pumps](https://openairdocs.org/ntsb-findings/01022822): Aircraft › Aircraft systems · Damaged/degraded (probable cause); cases with it: [Robinson Helicopter R44 II, 1 case](https://openairdocs.org/ntsb-findings/01022822/cases.md?model=7640122), [All aircraft, 71 cases](https://openairdocs.org/ntsb-findings/01022822/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute: Fuel contamination](https://openairdocs.org/ntsb-events/193) (defining event); cases with it: [Robinson Helicopter R44 II, 1 case](https://openairdocs.org/ntsb-events/193/sequence.md?model=7640122), [All aircraft, 225 cases](https://openairdocs.org/ntsb-events/193/sequence.md) - [Autorotation: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Robinson Helicopter R44 II, 95 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=7640122), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot of the helicopter was conducting an aerial observation flight when, about 250 ft above ground level (agl) and about 50 knots indicated airspeed, the engine lost total power. The pilot entered an autorotation, negotiated a powerline, and landed on a hill. During the landing, the helicopter rocked forward and aft, striking and substantially damaging the lower vertical stabilizer. Postaccident examination revealed water and a reddish-colored polyamide substance in the main fuel tank, auxiliary fuel tank, electric fuel pump, and gascolator. Further examination of the polyamide was inconclusive for a single known substance. The pilot reported that during the three-day mission, he refueled the helicopter at three different airports as well as his own personal fuel supply. Postaccident examination of the owner’s personal fuel supply and each of the airport’s fuel delivery systems did not reveal the presence of contamination. The circumstances of the accident are consistent with a total loss of engine power due to fuel contamination; however, the source of the contamination could not be determined based on the available information. ## Factual narrative On July 9, 2023, about 0947 central daylight time, a Robinson R-44 II helicopter, N163RK, was substantially damaged when it was involved in an accident near Marble Falls, Texas. The pilot and two passengers were not injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 aerial observation flight. The pilot reported that he was conducting a power pole inspection flight along with two non-pilot crewmembers. During the third day of the mission and while about 250 ft above ground level (agl) and about 50 knots indicated airspeed, the engine lost total power. The pilot entered an autorotation and turned right to an area suitable for a forced landing. During the descent, he saw a set of power distribution lines that crossed his path. He increased the collective control to clear the power lines and after he passed over the power lines, he felt a slight shudder. The helicopter touched down on slightly sloped terrain. During the touchdown, the helicopter rocked forward and aft. The lower vertical stabilizer contacted the ground, resulting in substantial damage. The pilot and crew exited unassisted. Examination of the helicopter revealed that both fuel tanks and the gascolator contained fuel along with a reddish-brown fluid that tested positive for water. According to a mechanic who performed postaccident maintenance on the helicopter, both fuel cells were coated on the inside with the red substance, and the electric fuel pump was clogged with the red substance. He stated that the red substance could only be dissolved with a methyl ethyl ketone (MEK) equivalent cleaner. The fuel samples were shipped to the NTSB Materials Laboratory for further examination. Further testing of the contaminated fuel samples revealed that the sample was consistent with a polyamide; however, a spectral library search did not find any strong matches to a single known substance. The pilot reported that he obtained fuel from several different airports as well as his own personal supply during the three-day mission; postaccident testing revealed no contamination in any of the fuel delivery systems. ## Aircraft - Registration: [N163RK](https://openairdocs.org/aircraft/N163RK), registered now, S/N 11120, built 2006 (OpenAirDocs) - Reported make and model: ROBINSON HELICOPTER COMPANY R44 II - Registry model: [Robinson Helicopter R44 II](https://openairdocs.org/model/robinson-helicopter-r44-ii) (registry code 7640122) (OpenAirDocs) - Registry engine: [Lycoming IO-540 series](https://openairdocs.org/engine/lycoming-io-540-series) (registry code 41530, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 11120 - Year built: 2006 - Airframe hours: 5590 - Engines: Lycoming IO-540-AE1A5 245 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial observation, Part 91 - Operator: Lone Star Aircraft Holdings LLC. - Registered owner: Lone Star Aircraft Holdings LLC. - Airworthiness certificate: Standard, Normal - Last inspection: Annual, June 16, 2023, 0 hours before - Departed: RYW, Lago Vista, TX - Equipment: ADS-B ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 46; injuries: none; flight instructor, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: helicopter, airplane; medical: class 2, without waivers/limitations; last flight review May 4, 2022; seat: right; restraint: 3-point; flight hours: 5,080 total, 1,603 in this make and model, 4,852 as pilot in command, 94 in the last 90 days, 34 in the last 30 days, 15 in the last 24 hours - Other flight crew; injuries: none; seat: right; restraint: 3-point ## Weather - Conditions: Visual (VMC), Day - Wind: 170° at 5 knots - Visibility: 10 statute miles - Temperature: 100 °F, dew point 61 °F - Altimeter: 29.87 inHg - Observed at: KDZB, 6 nm away - METAR: KDZB 092115Z AUTO 17005KT 10SM SCT080 38/16 A2987 RMK AO2 T03760164 ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20230709010329A](https://openairdocs.org/incident/20230709010329A), Jul 9, 2023: Robinson Helicopter Company R44 II, Marble Falls, TX, Substantial damage. While performing powerline inspection at 350 feet above ground level the engine failed. During the decent the tail rotor struck teh power line resulting in the… From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.